Coaxial resistor



Dec. 30, 1958 J. J. CERNY COAXIAL RESISTOR Filed Sept. 3, 1957 COAXIALRESISTOR Joseph J. Cemy, Chicago, Ill.

Application September 3, 1957, Serial No. 681560 4 Claims. (Cl. 201-63)The instant invention relates to electrical resistance devices and thelike. More particularly, it relates to a construction adapted for whatis referred to in the trade as a coaxial resistor.

A conventional coaxial resistor is a resistor or electrical resistanceconstruction which ordinarily comprises a bored core of some suitabledielectric material such as ceramic or the like. The core is usually ofcylindrcal configuration and has a resistance wire wound on and aboutthe outer curved surface. A pair of terminal wires extend outwardly fromthe bore of the core in opposite directions and axal alignment. Eachterminal wire is connected to an opposite end portion of the resistancewire. Conventionally a fused enamel or other suitable dielectric coatcovers the resistance wire and the core upon and about which theresistance wire is wound.

Various mechanical expedients have been conventionally 'employed tosecure the resistance wire to the terminal wires to provide rgidsecurance of the inner end portions of the .resistance wire within thecore and to securely fasten the resistance wire to the opposed terminalwires.

While the prior devices of the class described provide good resistors,their utility is frequently short-lived because they are ,unable towithstand extremes of physical handling, by reason of the fact that themechanism employed 'to connect the resistance wire to the end terminalwires changes the general geometric contour of such prior resistors.This variation in contour results in weakening, thinness or unevennessin the enamel coating conventonally covering the prior resistors,resulting in a predisposition or tendency for undesired grounding of theresistors.

Most suitably, the means for connecting the end termina wires to theresistance wire of a coaxial resistor should be some contrivance whichdoes not appreciably extend from or change the general cylindrcalcontour of the core. Thereby, when the enamel coat is fused about thecore and the resistance wire mounted thereupon, the enamel coat will befused without causing undesirable exposure of the resistance wireresulting from the adhesive characteristics of the enamelsconventionally used in connection with coating resistors.

In accordance with the instant invention and as an object thereof, thereis provided an electrical resistance construction or resistor in theclass described having means for connecting the resistance wire with theend terminal wires and being wholly within the general geometric contourof the core of the resistor.

It is a further object of the invention to provide an electricalresistance contruction or resistor comprising a core about which anelectrical resistance wire is wound and a pair of axially disposedterminal wires anchored within the core and extending outwardlytherefrom and means anchored within the cores secured to and elect t s.P nt ICC apparent from the following description and appended claims,reference being had to the accompanying drawings and numerals ofreference thereon.

On the drawings:

Fig. 1 is an exploded view showing the relationship of the resistorcore, the terminal wires and the connectors, the core being shown inlongtudinal section.

Fig. 2 is a longitudina] sectional view of a completed resistorillustrating one embodiment of the instant invention.

Referring now more particularly to the drawings, a core or base 10 isprovided which is of general cylindrical configuration. The core 10 isof some suitable dielectric fabrication such as a ceramic material, the

t coeflicient of expansion of which can be optionally varied inaccordance with requirement by varyng the compo sition of the materialscomprsing the fabrication.

The core 10 has provision for disposition therein of the inner endportions 11, 11 of a pair of axially disposed oppositely extendingterminal wires 12, 12. Such provision in the embodiment shown is bymeans of an axially disposed bore 13 extending longitudinally throughthe core 10. The bore 13 is preferably of a diameter substantially thesame or slghtly larger than the diameter of the terminal wires 12, 12 sothat the terminal wires may be readily manually inserted into theposition illustrated in Fg. 2 without permitting any substantial degreeof play of the portion of the terminal. wthin the core. Such arrangementprovides for 'coaxal disposition of the terminal wires.

In each of its opposite end portions, the core 10, in the embodimentillustrated, is provided with a diametric bore 14 which intersects theaxal bore 13 so that a pair of branch or radial bores extend outwardlyand perpendicularly from each end portions of the axal bore 13, asclearly illustrated in Fig. l. A metal plug or electrical connecter 15is positioned in each radial branch of the diametric bores 14.

In assembly of the resistor, the terminal wires 12, 12 are firstinserted within the axal bore 13. Thereafter the electrical connectors15, such as metal plugs, are inserted in their respective radial bores.The connectors 15 are Originally of a diameter substantially equivalentto or slghtly smaller than that of its respective bore 14, and they areof a length slghtly longer than or substantially equal to the radius ofthe core 10. That s to say, the connectors 15 when disposed in assembledposition as illustrated in Fig. 2 will rest upon their respectiveterminal wires and, at their outer ends, extend just slghtly beyond thesurface of core 10.

After arranging the foregoing parts, a resistance wire 16 is wound aboutthe core having certain portions or convolutions thereof in engagementwith the outer end of each Connector 15. Thereafter, with a weldingdevice (not shown), a number of strands of the resistance wire 16 arewelded to each connector 15 and each pair of connectors issimultaneously rigidly secured by welding to its respective terminalwire 12, as illustrated in Fig. 2. Because of the application of slightpressure during welding, the excess in length of each connecter 15 is&865379 forced back into its respective branch of bore l4. Such pressureinsures cngagement and subsequent welding of the inner ends of eachConnector with its respective terminal wire 12 and anchoring of therconnector within its respective bore, which it is adapted to fullyfill. I

. After assembly of the electrical components of the resistor, adielectric coat 17, such as an enamel frit s applied on and about theresistance wire 16' and .the ends of core 10 and subsequently fused. Byproper selection of the materials and their proportions, the coeicientof expanson of the enamel coat 17 can be selectively varied. p

Because of the confinement of the Components of .the assembly as closelyas possible to the general cylindrical configuration, crazing orcracking of and exposure of wire 16 because of the cohesivecharacteristics of the enamel coat 17 will be held to a minimum. Themost likely place of weakness in the instant Construction will be at theends of the core adjacent to the terminal wires 12, 12. Crazing orcracking of the enamel at these positions 18 will not afiect the life ofthe resistor as the resistance wire cannot be exposed at thesepositions.

As many changes or substitutions could be made in the above describedConstruction and as many apparently widely difierent embodiments of thenvention within the scope of the claims could be constructed withoutdeparting from the scope and spirit thereof, it is intended that anmatter contained in the accompanying specification shall be interpretedas being illustrative and not in a lmiting sense.

I claim:

1. An electrical resistance element comprising a passaged non-conductivecore; a resistance wire wound about said core; a pair of disconnectedelectrical terminals extending outwardly from said core, said corehaving a plurality of Connector-containing bores a''anged` in opposedradal pairs, each of said bores opening on the outer surface of and thepassage in said core; an electrical connector in eachconnecter-containing bore being of a length substantially equal to thelength of its respective bore, said connectors completely occupyingtheir respective bores and securing the terminals within said core andbeing Secured at their inner ends to said terminals and at their outerends to said resistance wire.

2. An electrical resistance element comprising a nonconductive core; aresistance wire wound about said core, said core having a longitudinallydisposed bore therein; a pair of opposed non-connected electrical endterminals disposed within said lonigtudinally disposed bore; two pair ofConnector-containing bores in said core arranged in pairs perpendicularto said longitudinal bore, each pair of said Connector-containing boresin association with one of said end terminals, respectively; electricalconnectors in said Connector-containing bores welded at their inner endsto said terminals and welded at their outer ends to'said resistancewire.

3. An electrical resistance element compr'sng a nonconductive core; aresistance wire on the outer surface of said core; a pair ofdisconnected electrical terminal wires extending outwardly from withinsaid core, said core having a pair of connecter-containing boresassociated with each terminal wire; an electrical connecter in eachConnector-containing bore being of a length substantially equal to thelength of its respective bore, said connectors Secured at their innerends to said terminal wires and at their outer ends to said resistancewire.

4. In an electrical resistance element of substantially singleresistance, the combination of an axially passaged non-conductive core,a resistance wre mounted about said core on the outer surface thereof;and a plurality of terminal wires extending co-axially from said core,with a pair of electrical 'connectors Secured at their inner ends toeach of the terminal wires the connectors of each pair being disposed ona common diameter, the outer and inner ends of said connectors beingsubstantially flush with the outer and inner surfaces of said core, saidconnectors, at their outer ends, Secured in electrical connection tosaid resistance wire.

References Cited in the file of this patent UNITED STATES PATENT S1,432,435 Abbott Oct.. 17, 1922 2,008,288 Malone July 16, 1935 2,063,826Pender Dec. 8,` 1936 2,773,159 Taggart --M-.-a Dec. 4, 1956

